QT interval dispersion in patients with chronic heart failure secondary to Chagas' cardiomyopathy: correlation with clinical variables of prognostic significance.

BACKGROUND: QTc interval dispersion has rarely been studied in patients with chronic heart failure (CHF) secondary to Chagas' cardiomyopathy. One study has demonstrated an association between QT interval dispersion and sudden cardiac death. No data exist regarding the association of clinical variables and QT interval dispersion in patients with this condition.

METHODS: Sixty three patients with CHF due to Chagas' cardiomyopathy, 34 Chagas' disease patients with no systolic dysfunction on echocardiography, and 36 individuals with no previous cardiac history, matched by sex and a 10-year age interval, were included in the investigation. The QTc interval dispersion was defined as the difference between maximum and minimum QTc.

RESULTS: The mean QTc interval dispersion was 74+/-30.3 ms in surviving and 87+/-30.6 ms in nonsurviving patients (P=.13). Mean QTc dispersion was 95.20+/-28.46 ms in patients who died from pump failure, 73.33+/-29.61 ms in patients who died suddenly, and 74.46+/-30.27 in survivors (P=.07). Mean QTc dispersion value was higher in patients in the Class III or IV (P=.01).). Mean QTc interval dispersion was 67.2+/-22.7 ms in patients with and 85.5+/-33.5 ms in patients without premature ventricular contractions (P=.01), and 67.5+/-29.8 ms in patients with and 84.7+/-31.8 ms in patients without left ventricular apical aneurysm (P=.03). A correlation could be observed in QTc interval dispersion and left atrium dimension (r=.32; P=.009) Thus, QTc interval dispersion is associated to some prognostic indicators in patients with CHF secondary to Chagas' cardiomyopathy.